import matplotlib.pyplot as plt
import numpy as np

r=2
a,b=(0,0)
theta = np.arange(0,2*np.pi, 0.01)
x = a + r * np.cos(theta)
y = b + r * np.sin(theta)
plt.figure(figsize=(10,10))
plt.plot(x,y)
r=2
a,b=(2,0.8)
theta = np.arange(-np.pi,0, 0.01)
x = a * np.cos(theta)
y = b * np.sin(theta)
plt.plot(x,y)
theta = np.arange(0,np.pi, 0.05)
x = a * np.cos(theta)
y = b * np.sin(theta)
plt.scatter(x,y,marker='_')
plt.scatter([0],[0],color='black')
plt.show()
